1. Field of the Invention
The present invention relates to a disk drive apparatus, preferably, a hard disk drive (HDD) employed as a data storing device of a computer. More particularly, the present invention relates to an HDD having a ramp shape that employs a head loading/unloading mechanism.
2. Description of Related Art of the Invention
The HDD is the most popular data storing means for computers. The HDD is structured so that a single or a plurality of magnetic disks are disposed on the same shaft and driven by a spindle motor therein. The capacity of the HDD is decided in accordance with the specifications of the subject computer in which the HDD is installed. Usually, the HDD is provided with one or more magnetic disks to satisfy the required capacity. For example, if 5 GB (gigabytes) is requested as the capacity of the HDD, five 1 GB magnetic disks (1 GB/disk) will be prepared. However, because there are a variety of computer specifications, 4 GB and 3 GB HDDs are also prepared.
The main components of a typical HDD are a magnetic disk and a spindle motor for driving the magnetic disk, and a case for holding and housing the magnetic disk, the motor, and other parts. This case is referred to as an enclosure case. One type of enclosure case can correspond to a plurality of capacity types. For example, if an enclosure case is designed in expectation that the HDD will be provided with five 1 GB magnetic disks so as to compose a 5 GB HDD, then the HDD will be provided with five 1 GB magnetic disks to comply with a requested capacity of 5 GB and with three 1 GB magnetic disks for a requested capacity of 3 GB. Such an HDD is referred to as a depopulation version HDD.
In a very compact and thin type HDD, for example, where the subject HDD is provided with a magnetic disk of 1 inch size, both sides of the magnetic disk are formed as recording surfaces and a magnetic head is prepared for each of those recording surfaces. If the capacity of one recording surface is 170 MB in such a thin type HDD, the HDD can have two capacity types; 340 MB and 170 MB. If a 340 MB HDD is defined as a standard one, the 170 MB HDD can be manufactured as a depopulation version of a 340 MB HDD in which only one side of the magnetic disk is used as a recording surface. In this case, the HDD has only one magnetic head for its one recording surface while the standard 340 MB HDD has two magnetic heads for its two recording surfaces.
Contact start-stop type disk drive apparatuses have been the main stream so far. In such a contact start-stop type disk drive apparatus, such a disk-like recording medium as a magnetic disk or the like is rotated, thereby generating an air bearing. The air bearing makes a head slider float from the surface of the disk so as to write data on the recording medium and read data from the recording medium. The head slider is mounted at a suspension arm composing a head arm of an actuator mechanism. In such a contact start-stop type HDD, however, the head slider is grounded on a save area on the disk surface when the rotation of the recording medium is stopped.
In a contact start-stop type disk drive apparatus, the head slider may possibly be sucked onto the surface of the data area and/or moved to the data area by a shock, thereby damaging the surface of the disk. To avoid such troubles and improve the reliability of the apparatus at the rest time, therefore, a load/unload type disk drive apparatus has been developed for commercial use. For example, such a load/unload type HDD is provided with a suspension arm for holding a magnetic head, as well as a part referred to as a ramp block. This HDD, while it is at rest, enables the ramp block to hold the suspension arm, thereby the head slider is prevented from touching the surface of the disk while the head slider is unloaded in the save area. The suspension arm has a load/unload tab having a projection and a ramp is formed at the ramp block. The ramp block is disposed so as to be close to the outer peripheral portion of the disk.
The loading/unloading mechanism, when the operation of the disk drive apparatus is stopped, rotates the suspension arm, thereby placing the projection of the load/unload tab of the suspension arm on the tab holding position so as to unload the head.
FIG. 6 shows a magnetic disk 150, a suspension arm 160, and a ramp 170. In FIG. 6, only one suspension arm 160 is shown so as to simplify the description for better understanding.
A load/unload tab 161 is formed at the suspension arm 160. The suspension arm 160 is rotated by a VCM (Voice Coil Motor not illustrated) in the radial direction of the magnetic disk 150, that is, towards 150A or 150B. At the ramp 170 are formed a load/unload surface consisting of a first slope surface 171, a flat surface 172, a second slope surface 173, and a supporting surface 174.
When data writing/data reading on/from the magnetic disk 150 is finished, the VCM rotates the suspension arm 160 towards 150B, that is, in the unloading direction. The load/unload tab 161 of the suspension arm 160 rubs against the flat surface 172 after climbing the first slope surface 171 of the ramp 170. The tab 161 then goes down the second slope surface 173 and stops on the supporting surface 174. At the time of starting writing/reading data on/from the magnetic disk 150, the load/unload tab 161 of the suspension arm 160, which has stopped on the supporting surface 174, climbs the second slope surface 173, then rubs against the flat surface 172, and goes down the first slope surface 171 to be loaded in the direction 150A.
Because the load/unload tab 161 of the suspension arm 160 rubs against the ramp 170 on the loading/unloading condition of the head, a friction torque is generated between them. Therefore, the driving force of the head driving mechanism including the VCM is determined by taking this friction torque into consideration.
In case of a 1-inch-diameter HDD as described above, if the HDD is provided with two magnetic heads, the HDD has two suspension arms 160. Therefore, if a friction torque Tf is generated when one suspension arm 160 climbs the second slope surface 173 on the loading condition of the head, the total friction torque will become 2Tf. Consequently, the head driving mechanism including the VCM must have a driving force enough to load the suspension arms 160 against this 2Tf.
However, if the HDD is a depopulation type one provided with only one magnetic head, the HDD has only one suspension arm 160. The total friction torque will thus become Tf. The head driving mechanism of the depopulation version HDD conforms to that of an HDD provided with two magnetic heads. At the time of loading the head, a current is applied to the VCM and when the suspension arm 160 reaches the flat surface 172, the speed of the suspension arm 160 is detected with use of the counter electromotive force of the VCM. After that, the speed of the suspension arm 160, that is, a current supplied to the VCM is controlled. Consequently, if the HDD is provided with only one magnetic head, thereby the total friction torque becomes a half of that of an HDD provided with two magnetic heads, then the suspension arm 160, that is, the magnetic head reaches the magnetic disk 150 before the power supplied to the VCM is controlled. As a result, the current might not be controlled in some cases.
In case of a 1-inch-diameter HDD, the HDD is manufactured basically as an analog of, for example, an 2.5-inch-diameter disk HDD. Consequently, the diameter of the coil composing the VCM becomes small just like in the 2.5-inch-diameter HDD. The counter electromagnetic force obtained from the VCM is in proportion to the square of the coil diameter. For example, if the diameter of the coil of a 2.5-inch-diameter HDD is 2.5 mm, the diameter of the coil of a 1-inch-diameter HDD is 1 mm. The counter electromagnetic force obtained from the 1-inch-diameter HDD is thus about 16% of that of the 2.5-inch-diameter HDD. Concretely, almost no counter electromagnetic force can be expected from the 1-inch-diameter HDD. Because the 1-inch-diameter HDD is thin in structure, the VCM is also thin. This is why the problem of the counter electromagnetic force appears more apparently.
When the power of an HDD is turned off abruptly, the head is unloaded usually with use of the counter electromagnetic force of the VCM, which is generated by a spindle motor. However, because almost no counter electromagnetic force can be expected from such a 1-inch-diameter HDD as described above, a method is proposed so that a current accumulated in a capacitor beforehand is supplied to the VCM, thereby unloading the head. The current supplied to the VCM at this time is the same between one-head HDD and two-head HDD. Consequently, if the friction torque is reduced, the speed of the suspension arm 160 is raised relatively on the unloading condition of the head. Such the HDD has been confronted with a problem that although the HDD is provided with a member referred to as an outer crush stop for limiting the suspension arm 160 in movement, the suspension arm 160, if the speed is fast, hits against the outer crush stop and bounces back onto the magnetic disk 150, thereby there is a problem that the apparatus cannot be started up.
Under such circumstances, it is an object of the present invention to provide a disk drive apparatus and manufacturing method thereof employed for a depopulation version HDD provided with less magnetic heads and suspension arms than the standard HDD so that the disk drive apparatus can control each magnetic head properly when the head is loaded and prevent the suspension arm from bouncing back onto the magnetic disk when its power supply is turned off.
The disk drive apparatus of the present invention is a depopulation version disk drive apparatus, comprising a disk-like medium for storing information; a head for writing/reading information on/from the disk-like medium; a suspension arm for supporting the head; a head driving mechanism for loading/unloading the head on/from the disk-like medium via the suspension arm; and a ramp for supporting the suspension arm when the head is unloaded and having a slope against which the suspension arm rubs when the head is loaded. The disk drive apparatus employs the same specifications as those of the standard disk drive apparatus except that the disk drive apparatus of the present invention is provided with less heads and less suspension arms than those of the standard disk drive apparatus. In addition, the disk drive apparatus of the present invention is composed so as to have the same friction torque between the ramp and the suspension arm as that of the standard disk drive apparatus when the head is loaded respectively. In order to make the friction torque equal between the depopulation version disk drive apparatus and the standard disk drive apparatus, the angle of the ramp slope surface of the depopulation version disk drive apparatus can be set larger than that of the standard disk drive apparatus. Concretely, because a friction torque is in proportion to a slope angle, the angle of the ramp slope surface of the depopulation version disk drive apparatus is set larger as described above, thereby increasing the friction torque.
It is another object of the present invention to provide a method for manufacturing a disk drive apparatus that employs a mechanism for loading/unloading the suspension arm provided with a read/write head onto/from a disk-like recording medium. This manufacturing method is intended for a series of hard disk drives wherein the number of heads is different mutually among them. The difference is based on the number of recording surfaces of the disk-like recording medium. A ramp is composed such that if the angle of the ramp slope surface of a series of disk drive apparatuses provided with less heads is defined as xcex11 and that of a series of the disk drive apparatuses provided with more heads is defined as xcex12, the relationship between those angles becomes xcex11 greater than xcex12.
For example, if a standard disk drive apparatus is provided with three disk-like recording media, then a disk drive apparatus provided with two or only one disk-like recording medium could become a depopulation version disk drive apparatus. In this case, the standard disk drive apparatus composes a series, the disk drive apparatus provided with two disk-like recording media composes another series, and the disk drive apparatus provided with only one disk-like recording medium composes further another series. The present invention can apply to such a series of disk drive apparatuses. Although the number of disk-like recording media is used for classifying series of disk drive apparatuses here so as to simplify the description, a disk-like medium enables recording surfaces to be formed on both face and back sides thereof. The number of recording surfaces may thus be used for classifying such series of disk drive apparatuses.
The above method for manufacturing a disk drive apparatus can apply to both series of disk drive apparatuses provided with less heads and series of disk drive apparatuses provided with more heads if the specifications of the mechanism for loading/unloading the suspension arm on/from a disk-like medium are the same between both series of disk drive apparatuses.
The disk drive apparatus and the disk drive apparatus manufacturing method of the present invention described above are preferred for a compact thin type HDD whose disk is 1 inch or under in diameter. Concretely, the present invention can provide a one-head hard disk drive, comprising a magnetic disk of 1 inch or under in diameter, provided with a magnetic recording layer on its one side; a magnetic head for writing/reading information on/from the magnetic recording layer of the magnetic disk; a suspension arm for supporting the magnetic head; a head driving mechanism for loading/unloading the head on/from the magnetic disk via the suspension arm; and a ramp for supporting the suspension arm when the head is unloaded, the ramp having a slope surface against which the suspension arm rubs when the head is loaded. Furthermore, in the one-head hard disk drive of the present invention, when it is compared with a two-head hard disk drive conforms thereto except that a magnetic recording layer is provided on both face and back surfaces of the magnetic disk, which is 1 inch in diameter, a pair of magnetic heads and suspension arms are provided so as to correspond to those face and back recording surfaces, and the ramp shape is different. The angle of the slope surface in the ramp of the former is set larger than that of the latter.
Furthermore, according to the present invention, it is possible to provide a new hard disk drive, comprising a magnetic disk of 1 inch or under in diameter, provided with a magnetic recording layer on its one side; a magnetic head for writing/reading information on/from the magnetic recording layer of the magnetic disk; a suspension arm for supporting the magnetic head; a head driving mechanism for loading/unloading the head on/from the magnetic disk via the suspension arm; and a ramp for supporting the suspension arm when the head is unloaded, the ramp having a load/unload surface against which the suspension arm rubs. In such a hard disk drive, the ramp can be provided with a limiter for limiting the suspension arm in vertical movement. In addition, the load/unload surface of the ramp can include a slope surface and the limiter can have a slope surface corresponding to the slope surface of the ramp.